Candidates in France's presidential election face a last-gasp push to overcome polls that suggest incumbent Emmanuel Macron is the clear favourite to win.
The first round of polling begins in about two weeks.
Mr Macron has been buoyed by his diplomacy and toughness on Russia since its troops invaded Ukraine, but has faced accusations of avoiding real debate.
Questioned on Sunday about his minimum campaigning, Mr Macron told broadcaster France 3 that "no one would understand at a moment when there's war" if he was out electioneering "when decisions have to be made for our countrymen".
Short of a major upset at the April 10 first round vote, Mr Macron's opponent in the run-off will be far-right National Rally leader Marine Le Pen, in a repeat of five years ago.
"Everything could be decided in the two weeks to come," with four in 10 likely voters still undecided, Adelaide Zulfikarpasic of the BVA Opinion polling group said.
Former columnist and TV commentator Mr Zemmour on Sunday rallied thousands of people waving French flags near the Eiffel Tower.
He called for more energy from his supporters in a speech that hit familiar notes of nostalgia for past French greatness and criticised immigrants who did not assimilate into French society.
"We've still got 14 days left. It's an eternity," Mr Zemmour said.
He said he was "the only candidate on the right".
Now trailing below 10 per cent in some polls, he is far short of Ms Le Pen's 20 per cent and Mr Macron at close to 30 per cent.
Ms Le Pen tried to project serenity as allies, including her niece Marion Marechal, deserted her for the tough-talking Mr Zemmour.
She has campaigned on French streets and market squares, and on Sunday again sought to appear more mainstream and competent than her rival.
"Eric Zemmour's programme is brutal in form but very limited in substance, whereas I have a draft law ready to be passed" on Islam and immigration, Ms Le Pen told weekly newspaper Le Journal du Dimanche on Sunday.
With those two battling for the hard-right and Mr Macron campaigning on business and law and order, Ms Pecresse has struggled to make herself heard.
Most recently, a positive Covid-19 test has kept her from planned campaign stops.
On Sunday, Mr Melenchon, who is polling at 12 to 15 per cent, rallied supporters in the Mediterranean port city of Marseille.
While left-wing resistance, including the 2018-2019 "yellow vest" protests, has dogged the presidency of Mr Macron, a host of competing candidacies from the left have not yet made a real mark on this year's election.
Mr Melenchon told the crowd that "we've suddenly said to ourselves, 'We're going to make it,'" into the second round.
"We're going to talk about serious things, not money fantasies like the one or racist fantasies like the other," he said.
Left-wing voters are split between Paris Mayor Anne Hidalgo, who is polling at about 2 per cent for the once-mighty Socialist Party, Communist candidate Fabien Roussel and Greens leader Yannick Jadot.
The woes of Ms Pecresse and Ms Hidalgo illustrate the longer-term factors beyond Ukraine that have affected French politics.
"The systematic voter who voted out of duty, the voter who was loyal and faithful to political parties or to candidates ... no longer exists," said Anne Muxel, research director at the Centre for Political Research in Paris.
"Voters have a much more independent, individualised relationship to politics and to their electoral choices. They're much more mobile, more volatile.
"The majority of French people don't feel represented by political office-holders."